<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
    .parent{
        width: 500px;
        height: 400px;
        border: 1px solid red;
        margin: 0 auto;
        display: flex;
        /*flex-direction: row;
        flex-wrap: wrap;*/
       /* flex-flow: column nowrap;*/
       /* justify-content: center;
       align-items: center; */
    }
    .child{
        /* width: 100px; */
        flex: 1;
        height: 60px;
        color: white;
    }
    .second{
        flex: 2;
    }
    </style>
</head>
<body>
    <!--仿网易云音乐app-->
    <div class="parent">
        <div class="child" style="background-color: red;">弹性元素1</div>
        <div class="child second" style="background-color: green;">弹性元素2</div>
        <div class="child" style="background-color: blue;">弹性元素3</div>
     <!-- <div class="child" style="background-color: red;">弹性元素1</div>
        <div class="child" style="background-color: green;">弹性元素2</div>
        <div class="child" style="background-color: blue;">弹性元素3</div>
     -->
    </div>
</body>
</html>